Abstract: A probe assembly for the measurement of moisture within a medium by indirect contact with the medium. The probe comprises an apparatus at the leading end of the probe to enable measurement of the moisture level within the medium. The apparatus comprises a thermal conductor linked to a heating source, a temperature sensor for enabling measurement of the heat dissipation rate in the thermal conductor upon isolation of the heating source and a heater for delivering energy from a power source to heat the thermal conductor via the heating source. The probe is surrounded by a controlled environment eliminating the need for pre-calibration of the probe. When the probe is inserted in the medium and the heater is isolated from the power source the heat dissipation rate is measurable and commensurate with the level of moisture in the medium.